The objective of these studies is to determine the relationship between the structure and the function of the ribosome in normal and cancerous eucaryotic cells. We will study the role of the ribosome in the following processes: protein synthesis, the control of protein synthesis, RNA synthesis, and the control of RNA synthesis in normal and cancerous eucaryotic cells to determine if there are any differences in these processes between normal and cancerous cells. Nutritional deprivation in conjunction with inhibitors and mutants that affect RNA and protein synthesis will be used to study the control mechanisms of RNA and protein synthesis. These studies will further define the precise mechanisms of RNA and protein metabolism in eucaryotic cells and will lead to a precise understanding of the mechanisms of action of the ribosome. The role of the ribosome in RNA and protein synthesis in conditional lethal mutants of eucaryotic cells will be analyzed at the cellular level, in vivo, by the following biochemical-physiological tests that we have developed or refined: incorporation of labelled precursors into DNA, RNA, protein and polysaccharide, polysome stability, and pulse-labelled RNA and protein entry into polysomes and other cell components. Differences in RNA and protein metabolism will be studied in vitro by biochemical tests we have developed to characterize conditional lethal mutants defective in protein synthesis in yeast. This approach - first in vivo tests, then specific in vitro tests, will also enable us to determine the precise mechanisms of action of antitumor agents that affect RNA and protein synthesis. Conditional lethal mutants of mammalian cells will be isolated and analyzed to locate their precise defect. These tests will be applied to the following mammalian cell lines: mouse BALB/3T3 cells, Hamster CHO and human, Hela cells; and to the eucaryotic organism, Saccharomyces cerevisiae. Mutant isolation will be restricted to the CHO cell lines and S. cerevisiae.